Generally, there are numerous multilamp photoflash arrays wherein series and parallel-connected lamps are sequentially fired. Such arrays frequently involve heat sensitive switching devices which react to a proximate radiant energy output and respond by melting, fusing or reacting chemically to alter an electrical circuit path from a normally conductive to a normally non-conductive state.
Examples of the above-described arrays are presented in numerous U.S. patents, and a particular example is U.S. Pat. No. 3,532,931 of Cote et al wherein current-sensitive switches are in series connection with individual flashlamps. Another example is found in U.S. Pat. No. 3,692,995 of Wagner wherein fuses are connected in series with each lamp and upon ignition of a selected lamp develop sufficient heat to melt the fuse and remove a short circuit across the next lamp in sequence.
A further example of radiant energy responsive switches which fuse, melt or react chemically to provide a non-conductive electrical path is set forth in U.S. Pat. No. 4,017,728 of Audesse et al. Therein, a plurality of normally conductive switches are fabricated from a heat shrinkable polymeric material and positioned in operative relationship to a flashlamp or radiant energy source. Upon activation of the radiant energy source, the mid-portion of the normally conductive switch, which bridges an aperture rapidly shrinks and separates. Thus, an electrically conductive path is rendered electrically non-conductive and provides an open circuit to applied voltages.
Normally, the above-described switches are fabricated and affixed to a printed circuit board as individual switches with the switch material cut to size and affixed at opposite ends to a pair of switch contacts. However, it has been found that such techniques for fabricating arrays become extremely difficult, if not impossible, when a miniaturized array is under consideration. More specifically, miniaturized arrays have a relatively narrow space between switches as well as a relatively small space between the switch contacts. Thus, it becomes most difficult to handle and position a relatively small piece of switch material on a miniaturized multilamp photoflash array.